The unidentified family had been sailing a small vessel west of Monterey Bay, where strong winds, cold water and big swells made for perilous conditions. Forecasters had issued a weekend advisory warning boaters of rough seas in the area.

The group — which included two children under 8 — made its first distress call late Sunday afternoon, Coast Guard Lt. Heather Lampert said. Investigators used the boat’s radio signal and radar to determine the call came from an area about 60 miles west of Monterey, she said.

The boaters reported that their 29-foot sailboat was taking on water and the electronics were failing.

An hour later, the family members reported they had to abandon the boat and were trying to make a life raft out of a cooler and life-preserver ring, Lampert said. The Coast Guard then lost radio contact.

The agency looked for the family through the night and on Monday, with help from the California Air National Guard.

The Coast Guard on Monday also released one of the family’s recorded distress calls, in hopes that it will lead to new information from the public that could help in the search. So far the agency has received no reports of missing persons in the case.

The agency believes the boat may have been called “Charmblow.” In the crackling recording, a man’s voice is heard saying, “Coast Guard, Coast Guard, we are abandoning ship. This is the (Charmblow), we are abandoning ship.”

The agency has not identified the family, although investigators were able to determine from the broken distress calls that they were a husband and wife, their 4-year-old son and his cousin, Lampert said.

The family’s location initially was reported farther north, but Lampert said investigators using the boat’s radio signal and radar now believe the call came in west of Monterey Bay, which is about 100 miles south of San Francisco. The boat did not have a working GPS system.

The National Weather Service had issued an advisory throughout the weekend warning boaters of strong winds and rough seas around the San Francisco Bay Area. Water temperatures in the area typically are in the 40s and 50s, making long-term survival difficult.

Mariners “operating smaller vessels should avoid navigating in these conditions,” the advisory said.

Calls to harbors in California have failed to locate the boat, and database searches have come up empty too, Lampert said. The Coast Guard was expanding its search to Hawaii, the Seattle area and north into Canada.